Nitrocellulose doublebase propellant containing ternary mixture of nitrate esters

ABSTRACT

A nitrocellulose base propellant containing trimethylolethane trinitrate, triethyleneglycol dinitrate, and diethyleneglycol dinitrate.

United States Patent [191 Zucker et al.

[4 1 Feb. 18, 1975 1 NITROCELLULOSE DOUBLEBASE PROPELLANT CONTAINING TERNARY MIXTURE OF NITRATE ESTERS [75] Inventors: Jonas Zucker, West Orange; Russell Trask, Morris Plains, both of N.J.; Edward Costa, Brooklyn, NY.

[73] Assignee: The United States of America as represented by the Secretary of the Army, Washington, DC.

[22] Filed: Sept. 18, 1967 [21] Appl. No.: 669,359

[52] U.S. Cl 149/100, 149/94, 149/96 [51] Int. Cl C061) 5/00 [58] Field of Search 149/88, 89, 98, 91, 94,

[56] References Cited UNITED STATES PATENTS 3,033,716 5/1962 Preckel 149/96 Primary Examiner -stephen ,1. Lechert, Jr. Attorney, Agent, or FirmEdward J. Kelly; Herbert Berl; Edward F. Costigan [57] ABSTRACT A nitrocellulose base propellant containing trimethylolethane trinitrate, triethyleneglycol dinitrate, and diethyleneglycol dinitrate.

9 Claims, N0 Drawings 1 NITROCELLULOSE DOUBLEBASE PROPELLANT CONTAINING TERNARY MIXTURE F NITRATE ESTERS This invention relates to an improved nitrocellulose base propellant containing a series of mixed nitrates.

As a result of the advance design of the special highpressure propulsion systems in use today, a propellant to perform satisfactorily in such systems must provide a relatively high force for use in propelling the missile to the target desired accompanied by a relatively lower isochoric flame temperature. If a relatively high tem' perature accompanies the force produced, the propulsion tubes of the system involved will begin to erode after, as little as, two or three firings. Also, if too little force is produced upon firing, the missile involved will not perform well with regard to range under the ordinary conditions encountered with the special highpressure propulsion systems in use today.

However, many of the standard artillery propellants, although exhibiting the desired force and flame temperature, also exhibit highly erratic burning rate characteristic when fired in the high-pressure propulsion systems in use today. Activity such as that above is especially prevalent for the triple-base, nitroquanidine, compositions which are especially unsatisfactory for high-pressure propulsion systems due to their tendency to disintegrate or break-up under high pressure resulting in uncontrolled deflagration and gun destruction. Further, the double-base propellants containing nitrocellulose and nitrogylcerin were utilized in lieu of the triple-base compounds. However, although these compositions do not disintegrate under pressure, they have a high isochoric flame temperature and a relatively lower force when compared to norm desired for the high pressure propulsion systems in use.

Therefore, it is an object of this invention to provide an improved nitrocellulose base propellant composition which is of use in high-pressure propulsion systems.

Another object is to provide a propellant composition for use in a high-pressure propulsion system which exhibits the desired force and flame temperature upon ignition.

Another object is to provide a propellant composition for use in a high-pressure propulsion system which is not subject to disintegration and does not tend towards gun destruction upon firing.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description.

It has now been discovered that a nitrocellulose base propellant may be produced which possesses the physical strength of the conventional double-base propellant. and the gas volume-temperature relationship of the conventional triple-base propellant, accompanied by the desired level of force, and the desired degree of flame temperature for optimum use in a high-pressure propulsion system. This is accomplished by the incorporation of a specific series of nitrate esters into the nitrocellulose basc propellant during manufacture. The propellant produced is a homogeneous, colloided propellant without any physical stresses or strains and having a uniform burning rate accompanied by a relatively lower isochloric flame temperature at a high gas volume to maintain an acceptable specific force.

The nitrate esters which, in combination, may be utilized to advantage in a nitrocellulose base propellant composition include trimthylolethane trinitrate referred to as TMETN; triethyleneglycol dinitrate referred to as TEGDN; and diethyleneglycol dinitrate referred to as DEGDN. The following may be substituted for the above basic nitrates with equivalent results in the areas desired, viz:

l. Nitroisobutylglycerol trinitrate may be substituted for TMETN,

2. Glycol Dinitrate may be substituted for DEGDN, and

3. Glycerol Monolactate Trini'trate may be substituted for TEGDN.

As noted above, the specified nitrate ester which may be used in combination include TMETN, TEGDN, AND DEGDN. Of which, DEGDN improves the force produced by the propellant upon explosion, while TMETN improves gas volume, tending also to improve force, and TEGDN improves the physical properties at low temperatures. These esters may be utilized in the following weight per cents to produce an acceptable propellant, viz:

TMETN 14.375 to 35.625. TEGDN 5.750 to 14.250. DEGDN 2.875 to 7125.

If we go above these specified percentages in the normal propellant, the propellant would be rather soft and would cause a loss of grain shape. Below these percentages, in the nonnal propellant, the composition would be too hard for extrusion or rolling purposes. The preferred ranges in weight per cent are as follows, viz:

TMETN 20.0 to 30.0. TEGDN 8.0 to 12.0. DEGDN 4.0 to 6.0.

The preferred ranges of materials when incorporated into a propellant yield the optimum with respect to force and isochoric flame temperature. Within this range, highly satisfactory results were obtained with respect to reproducibility from lot to lot of the same composition when the weight percentages of the nitrates ester were in the following ranges, viz:

TMETN 24.0 to 26.0. TEGDN 9.6 to 10.4. DEGDN 4.8 to 5.2.

In general, the propellant composition of this invention may be prepared for use in the manner described below.

EXAMPLE 1 Nitrocellulose having a nitrogen content of l3.15 i 0.05 percent is added to a conventional sigma blade mixer in an amount between about 58 to 62 percent by weight along with a maximum of 1.0 percent of inorganic salt such as potassium sulfate: or potassium aluminum fluoride or sodium aluminum fluoride (cryolite) for flash reduction. The materials are then mixed for 5 to 10 minutes before adding the remaining ingredients. A mixture of 37 to 40 percent by weight of the mixed nitrate esters of the specific combination described are then added to the mixer and agitated for about 5 minutes. At this point, 1.5 percent of a stabilizer such as diethyldiphenylurea (ethyl centralite) or 2- nitrodiphenylamine which is wetted with alcohol is added and agitation continued for minutes. Solvents making up 55 to 65 weight percent of the total composition are then added to the mixture. This liquid component should consist of 40 to 50 parts by weight ether and'50to "60 parts by weight alcohol. Afterthe solvents are added, mixing should be continued for a maximum of 3 hours at approximately 60 to 100F. As a result of the above processing, a uniform, extrudable colloid is produced which may be treated in the conventional manner to form specific grain geometries. For instance, the colloid may be pulled from the mixer, transferred Obviously, many modifications and variations of the present invention are possible in the light of the above teaching. It is, therefore, to be understood that within the scope of the appended claims, the invention may be 5 practiced otherwise than as specifically described.

We claim: 1. In a double base propellant composition containing nitrocellulose, the improvement consisting of the incorporation in said propellant composition of one of r the ternary mixtures of nitrate esters selected from the Trimethylolethane trinitrate, triethyleneglycol dini- I to a press, blocked, screened, reblocked, extruded l5 trate d l l di it t through dies of the deslred dlmenslon Cut to the Trimethylolethane trinitrate, glycerol monolactate stred length and d 'ledtrinitrate and diethyleneglycol dinitrate;

Depending upon the applicat of the n Item, the Trimethylolethane trinitrate, glycerol monolactate dried propellant may be glazed with 0.1 percent graphtrinitrate d l l di i 2O Nitroisobutylglycerol trinitrate, glycerol monolactate The composltions 2,584 and 2,586 set forth 1n the tri itrate, and diethyleneglycol dinitrate; table below, WhlCh are Included wlthm the Scope of thls Nitroisobutylglycerol trinitrate, glycerol monolactate invention, may be utilized as new solid propellants for i it t d ly l dinitrate; use In an y round- The)! are mpa Wlth Nitroisobutylglycerol trinitrate, triethyleneglycol di-, spect to their thermochemical characteristics and physnitrate d di h l l l di i t lcal P p to the Standard p base, and Nitroisobutylglycerol trinitrate, triethyleneglycol di- M26El, double base propellants in use today. nitrate, d l l di it t TABLE 1 Propellant M30 M26E1 Expt 2584 Exp! 2586 Composition (percent by weight) Nitrocellulose 28.0 68.7 61.5 58.5

Nin NC) (12.6) (13.15) (13.15) (13.15) Nitroglycerin 22.5 25.0 Trimethylolethane trinitrate 25.0 25.0 Triethyleneglycol dinitrate 12.0 10.0 Diethyleneglycol dinitrate 5.0 Nitroguanidine 47.7 Ethyl Centralite 1.5 6.0 1.5 1.5 Cryolite 0.3 0.3(Add) 0.3(Add) Graphite 0.3 Graphite (glaze) 0.1 0.1 0.1 Residual Water 0.0 0.2 0.5 0.5 Residual Ethyl Alcohol 0.3 0.7 0.5 0.5

Thermochemicals Characteristics lsochoric Flame Temperature, K 3040 3130 3008 3030 Force, ft-lbs/lb 364,500 302,000 362,800 365,700 Heat of Explosion, cal/gm 974 977 944 955 Unoxidized Carbon, percent 3.2 1.5 3.7 3.7 Combustibles (CO+H2), percent 41.0 56.3 58.0 57.6 Gas Volume, moles/gram 0.04308 0.04164 0.04336 0.04339 Propellant M30 M26E1 Mechanical Properties Temp, F 145 70 145 -40 Maximum Stress, psi 2733 5883 19995 6780 12637 22068 Compression at Max Load, 7: 19.0 14.9 8.2 61.0 55.9 8.3

Expt 2584 Expt 2586 Temp., "F 70 40 145 70 40 Maximum Stress, psi 3618 8963 19633 2850 6850 16140 Compression at Max Load, 67.9 61.6 41.4 73.3 67.6 42.3

It is to be noted that the isochoric flame temperature 3 of the new propellants are below those of the standard propellants and yet, the force values are comparable for all propellants. Also, the presence of the mixed nitrate esters TMETN and TEGDN, with or without 2. The composition of claim 1 wherein said mixed nitrate esters are trimethylolethane trinitrate, triethyleneglycol dinitrate, and glycol dinitrate.

3. The composition of claim 1 wherein said mixed nitrate esters are trimethylolethane trinitrate, glycerol DEGDN, result in vastly improved values in the areas 65 monolactate trinitrate, and diethyleneglycol dinitrate.

desired for the new compositions at low temperature.

4. The composition of claim 1 wherein said mixed ni;

trate esters are trimethylolethane trinitrate, glycerol monolactate trinitrate and glycol dinitrate.

5. The composition of claim 1 wherein said mixed nitrate esters are nitroisobutylglycerol trinitrate, triethyleneglycol dinitrate and diethyleneglycol dinitrate.

6. The composition of claim 1 wherein said mixed nitrate esters are trimethylolethane trinitrate, triethyleneglycol dinitrate and diethyleneglycol dinitrate.

7. The composition of claim 6 wherein said trimethylolethane trinitrate is present in an amount between about 14.375 and 35.625 percent, said triethyleneglycol dinitrate is present in an amount between about 5.750 and 14.250 percent, and said diethyleneglycol dinitrate is present in an amount between about 2.875 and 7.125 percent, all said percents being by weight.

8. The composition of claim 6 wherein said trimethylolethane trinitrate is present in an amount between 20 to 30 percent, said triethyleneglycol dinitrate is present in an amount between 8 and 12 percent, and said diethyleneglycol dinitrate is present in an amount between about 4 and 6 percent, all said percents being by weight.

9. The composition of claim 6 wherein said trimethylolethane trinitrate, is present in an amount between about 24 to 26 percent, said triethyleneglycol dinitrate is present in an amount between 9.6 and 10.4 percent and said diethyleneglycol dinitrate is present in an amount between about 4.8 and 5.2 percent, all said percents being by weight. 

1. IN A DOUBLE BASE PROPELLANT COMPOSITION CONTAINING NITROCELLULOSE, THE IMPROVEMENT CONSISTING OF THE INCORPORATION IN SAID PROPELLANT COMPOSITION OF ONE OF THE TERNARY MIXTURES OF NITRATE ESTERS SELECTED FROM THE GROUP CONSISTING OF: TRIMETHYLOLETHANE TRINITRATE, TRIETHYLENEGLYCOL DINITRATE AND DIETHYLENEGLYCOL DINITRATE, TRIMETHYLOLETHANE TRINITRATE, TRIETHYLENEGLYCOL DINITRATE AND GLYCOL DINITRATE, TRIMETHYLOLETHANE TRINITRATE, GLYCEROL MONOLACTATE TRINITRATE AND DIETHYLENEGLYCOL DINITRATE, TRIMETHYLOLETHANE TRINITRATE, GLYCEROL MONOLACTATE TRINITRATE AND GLYCOL DINITRATE, NITROISOBUTYLGLYCEROL TRINITRATE, GLYCEROL MONOLACTATE TRINITRATE, AND DIETHYLENEGLYCOL DINITRATE, NITROISOBUTYLGLYCEROL TRINITRATE, GLYCEROL MONOLACTATE TRINITRATE, AND GLYCOL DINITRATE, NITROISOBUTYLGLYCEROL TRINITRATE, TRIETHYLENEGLYCOL DINITRATE AND DIETHYLENEGLYCOL DINITRATE, NITROISOBUTYLGLYCEROL TRINITRATE, TRIETHYLENEGLYCOL DINITRATE, AND GLYCOL DINITRATE.
 2. The composition of claim 1 wherein said mixed nitrate esters are trimethylolethane trinitrate, triethyleneglycol dinitrate, and glycol dinitrate.
 3. The composition of claim 1 wherein said mixed nitrate esters are trimethylolethane trinitrate, glycerol monolactate trinitrate, and diethyleneglycol dinitrate.
 4. The composition of claim 1 wherein said mixed nitrate esters are trimethylolethane trinitrate, glycerol monolactate trinitrate and glycol dinitrate.
 5. The composition of claim 1 wherein said mixed nitrate esters are nitroisobutylglycerol trinitrate, triethyleneglycol dinitrate and diethyleneglycol dinitrate.
 6. The composition of claim 1 wherein said mixed nitrate esters are trimethylolethane trinitrate, triethyleneglycol dinitrate and diethyleneglycol dinitrate.
 7. The composition of claim 6 wherein said trimethylolethane trinitrate is present in an amount between about 14.375 and 35.625 percent, said triethyleneglycol dinitrate is present in an amount between about 5.750 and 14.250 percent, and said diethyleneglycol dinitrate is present in an amount between about 2.875 and 7.125 percent, all said percents being by weight.
 8. The composition of claim 6 wherein said trimethylolethane trinitrate is present in an amount between 20 to 30 percent, said triethyleneglycol dinitrate is present in an amount between 8 and 12 percent, and said diethyleneglycol dinitrate is present in an amount between about 4 and 6 percent, all said percents being by weight.
 9. The composition of claim 6 wherein said trimethylolethane trinitrate, is present in an amount between about 24 to 26 percent, said triethyleneglycol dinitrate is present in an amount between 9.6 and 10.4 percent and said diethyleneglycol dinitrate is present in an amount between about 4.8 and 5.2 percent, all said percents being by weight. 